“Their Finest,” the latest from Danish director Lone Scherfig (“Italian for Beginners”), takes that admittedly amusing self-absorption and pumps it up with World War II-era nostalgia and nascent female empowerment.

In Blitz-ravaged London, copywriter Catrin Cole (Gemma Arterton) lands the gig of a lifetime. She’s hired by the Ministry of Information’s Film Division to write a feature film — one that is both “authentic and optimistic” — that will embody Britain’s can-do spirit in the face of Hitler’s juggernaut.

The film is intended as pan-Atlantic propaganda that will show war-wary American audiences that Britain is more than supercilious aristocrats, that it’s a nation of everyday men and women fighting heroically for survival.

Catrin finds her subject in the real-life experiences of two spinster sisters who stole their drunken uncle’s boat and became part of the mass evacuation of British troops from Dunkirk in France.

Though she already has a significant other (Jack Huston, playing an unsuccessful painter of glum cityscapes), Catrin finds intellectual stimulation (and other sorts as well) in her new writing partner, Tom Buckley (Sam Claflin). He’s one of those seen-everything cynics who nevertheless knows exactly how to manipulate an audience (“Film is real life with the boring stuff cut out”).

Together they figure out how to cajole a fading matinee idol (Bill Nighy, playing the sort of jaded egomaniac he does so well) into taking the seemingly inconsequential role of the drunken uncle. Somewhat more perplexing is how they are to satisfy the Ministry by creating a character for a non-acting American (Jake Lacy) who has been flying missions for the R.A.F.